Zeolites with the framework structure BEA (zeolite beta) doped with tin have shown promising results if used as catalytically active materials in certain applications such as BaeyerVilliger-type oxidation reactions, isomerization reactions, and the like.
According to the known literature, tin containing zeolites having BEA framework structure BEA are usually prepared by incorporation of tin into the zeolitic framework by hydrothermally treating a zeolitic material having vacant tetrahedral framework sites in the presence of tin-ion source. However, regarding this hydrothermal incorporation of tin, disadvantages have to be taken into account such as long synthesis time periods, the necessity to employ crystallization auxiliaries such as HF or cost intensive templating agents. Still further, only tin containing zeolites having BEA having a low tin content could be obtained.
Hammond et al. describe a process for the preparation of zeolites with the framework structure BEA which are prepared by incorporating tin into the zeolitic framework having vacant tetrahedral framework sites by a specific solid-state ion exchange process wherein said zeolitic framework having vacant tetrahedral framework sites is suitably mixed together with a solid tin-ion source. While the process described in Hammond et al. provides certain advantages compared to the previously known processes for the preparation of tin-containing zeolites having BEA framework structure, the testing of the respectively obtained material in BaeyerVilliger-type oxidation reactions which are explicitly mentioned in Hammond et al. did not show desired selectivities to the reaction product. Further, the process as such included certain reaction steps which, in particular in view of an industrial-scale process for the preparation of a zeolitic BEA framework having vacant tetrahedral framework sites, are not necessarily a realistic option, such as the dealumination via an acid treatment.